1. Field of the Invention
The present invention relates to an audio system, in which a signal line path is set by the medium of an audio device and an external device using a universal serial bus (USB) or an expansion connector, a digital audio file stored in the external device is uploaded according to a user's manipulation, and sound is outputted through the audio device.
In addition, the present invention relates to a USB/UART common communication system, in which USB and UART connection signals are automatically detected using a single USB connector, and USB and UART communications can be selectively used by using the detected USB and UART connection signals as a common signal line.
Further, the present invention relates to a USB/UART common communication system, in which a connector of an external device and an audio/USB/UART common connector are connected through a single cable and an audio device selectively outputs an audio/USB or audio/UART signal through a common audio signal line.
2. Description of the Related Art
As various media players become popular, consumers increasingly want to listen to songs stored in a media player through a speaker system of a car audio or home audio device. To this end, an FM transmission function is added to a conventional media player such that a song played by a media player is transmitted over a specific FM frequency. Further, an audio device outputs an audio signal through frequency tuning in an FM reception mode.
In addition, an Aux-line in a conventional audio device is separately extended and connected to an earphone jack of a media player. Like this, as digital media technologies become popular, consumers increasingly want to directly play digital contents stored in a USB memory through a speaker system of a car audio or home audio device.
To this end, there is a patent application entitled “A MEDIAL PROCESSING DEVICE USING AN EXTERNAL STORAGE DEVICE”, filed by the present applicant on Apr. 4, 2002 (Korean Patent Application No. 2003-21307) and issued on Oct. 15, 2003 (Korean Patent Registration No. 403,376). According to this patent, an audio device includes a USB host interface to directly read and play contents stored in a USB memory.
A media storage or media player using the above-described digital media technology includes a product group of MP3 player or USB flash disk (UFD) using a standard USB, and a product group of Apple iPod using universal asynchronous receiver/transmitter (UART) and IEEE 1394 as an interface.
In the Apple iPod illustrated in FIG. 1, an MP3 player 10 includes a 32-pin connector 11 and an IEEE 1394 connector 12. The IEEE 1394 connector 12 is connected to an Apple PC and used to download an MP3 file. The MP3 player 10 is connected to a remote controller and used to control the device in a UART communication scheme and display song information.
In addition, as illustrated in FIG. 2, the 32-pin connector 11 of the MP3 player 10 is connected to a 32-pin connector 21 additionally installed in a car audio 20. The car audio 20 receives song information in a UART communication scheme and provides device control information to the MP3 player 10. In this way, a car audio package using the 32-pin connector is provided. Such a car audio is called an “iPod ready” and an analog audio is separately connected through an Aux-line.
In recent years, USB connectors tend to be mounted in the car audio. Therefore, in order to implement the iPod ready or UART communication, the car audio must include both an expansion connector and a USB connector, causing space deficiency and design problem.
Because the Apple iPod can be connected only through a dedicated interface and a player using the UART communication has an expansion connector and a USB connector different from each other, there is a limit in using the conventional scheme, if the interface of the car audio is not additionally provided. Although consumers purchase a lot of the Apple iPods or UART communication products, the utilization is not high.
Moreover, USB, UART, and AUDIO connectors are separately provided in the existing car audio or home audio system. Thus, when the USB and the AUDIO connectors are used, a USB cable and an AUDIO cable must be separately used. In addition, when the UART and AUDIO connectors are used, a UART cable and an AUDIO cable must be separately used.